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Friday, June 22, 2012

Sentient plants?

Economist Gene
Callahan (a friend of this blog) calls my attention to this
article, which claims that plants are capable of “sensory” responses to
their environments, and even that they “talk and listen to one another.” Gene
concludes that “contrary to Aristotle, plants are active and communicate to
each other, with sounds among other methods” so that “neo-Aristotelians ought
to drop the idea that plants lack sensations.”
And while Gene allows that “this certainly does not invalidate all of
Aristotle's metaphysics,” it does in his view show that Aristotelians should be
wary of once again “ma[king] the mistake of tying Aristotelian metaphysics to
Aristotelian natural science.”

But (no disrespect to Gene intended) as usual
with these breathless journalistic “Science has shown that…!” stories, the actual
facts are far less exciting than the sensationalistic packaging would suggest.

What the
article describes when it gets down to the details is the following:

Using powerful loudspeakers,
researchers at The University of Western Australia were able to hear clicking
sounds coming from the roots of corn saplings.

Researchers at Bristol University
also found that when they suspended the young roots in water and played a
continuous noise at 220Hz, a similar frequency to the plant clicks, they found
that the plants grew towards the source of the sound…

[P]revious research from Exeter
University found cabbage plants emitted methyl jasmonate gas when their
surfaces are cut or pierced to warn its neighbors of danger such as
caterpillars or garden shears.

Researchers from the earlier study
also found that the when the volatile gas was emitted, the nearly cabbage
plants appeared to receive the urgent message that [sic] and protected
themselves by producing toxic chemicals on their leaves to fend off predators
like caterpillars.

What has
been shown, in other words -- if these claims are correct, anyway -- is that
plants are sensitive to sounds (or at least to the vibrations associated with
sounds) and to gases. But so what? Aristotelians, like everyone else, have long
known that plants are in various ways sensitive to their environments -- that
they will grow toward light, sink their roots in the direction of water, etc. They have long known how a Venus fly trap
will react to the presence of an insect and how the Mimosa pudica will respond to touch. And they have long had a response to those
who falsely suppose that these sorts of phenomena imply sentience. Gene seems to think the article in question
provides cutting-edge scientific evidence that “whether anything at all has a ‘vegetative
soul’… it ain't plants.” Yet the objection
he raises is explicitly dealt with in books like George Klubertanz’s 1953 volume
The Philosophy of Human Nature and
Henry Koren’s An Introduction to the
Philosophy of Animate Nature, published in 1955. The subject is also treated at some length in
David Oderberg’s recent Real
Essentialism (at pp. 183-93).
What we have here, in the case of criticism of the Aristotelian conception
of vegetative life (and with all due respect to Gene), is something often seen in criticism of Aristotelian ideas
in natural theology, philosophy of mind, and ethics -- namely a failure to
understand what Aristotelian writers actually mean by the technical terms they
use, or to bother to read what they’ve written so as to find out what they
mean.

What Aristotelians
do mean when they deny sentience to plants
is not that plants are incapable of receiving information from their environments
in ways that are in some respects analogous to sensation, but rather that in plants,
unlike animals, there is no conscious
awareness associated with the reception of this information. In other words, what they mean is that there
are nothing like qualia in plants, as
there are in animals. There’s something
it’s like to be a bat, a dog, or a bird; but there’s nothing it’s like to be a tree,
a blade of grass, or even a Venus fly trap.
That roots grow toward water doesn’t entail that plants feel thirst, and
that plants grow toward light doesn’t entail that they feel heat or see the
sunshine. Similarly, if some plants are sensitive
to vibrations and gases, it doesn’t follow that they hear or smell.

Nor is the
reason Aristotelians would deny awareness to plants a matter of dogmatic a
priori metaphysics (though metaphysical considerations have something to do
with it). As always when determining the
natures of things, we must, for the Aristotelian, stick to the empirical
evidence. Koren writes:

It would be irrational to admit potencies
implying awareness in plants if they do not show any signs of awareness, for
one does not admit anything for which there is no evidence. But in plants there are no signs of activity
involving awareness. Therefore, we
cannot admit that plants have any potencies implying awareness, such as sensation
and intellection.

The minor premise of this argument is attacked by opponents who point to
so-called tropisms in plants, i.e. to the way they respond to physical stimuli…
(p. 72)

Examples of
the sort already mentioned follow, after which Koren says:

These facts would settle the argument
in favor of sensation if they could be explained only as responses following upon the awareness of the physical stimulus by which they are provoked. But if these
facts can be explained equally well without awareness, as purely physical and mechanical responses to physical
stimuli, this explanation has to be preferred, because it would be unreasonable
to assume the working of a higher cause for effects which can be explained
equally well by a lower cause.
(Ibid.)

Yet there is
simply nothing in the phenomena in question that requires attributing awareness
to plants as opposed to mere unconscious sensitivity to certain specific
environmental triggers (of the sort evident in, say, a smoke alarm or an
outdoor security lamp). Moreover, as Aristotelian
writers emphasize, there are at least three key aspects of sensation in animals
that are absent in the case of plants. First
of all, there are in animals specialized sense
organs associated with their various forms of awareness -- eyes with visual
awareness, ears with hearing, and so forth.
There is nothing like that in the case of plants.

Second, sensation
in animals is associated with a variability
of response that is not present in plants.
Unless it is in some way damaged, a plant will, say, simply grow toward
the light or sink its roots downward in response to the relevant stimuli. A properly functioning animal, by contrast,
may respond in a number of different ways to stimuli presented to it. For example, an animal might immediately leap
toward the prey it sees, or sneak up toward it slowly, or refrain from acting
at all if it sees another, stronger predator in the vicinity or some barrier it
is afraid to cross. A conscious perception
functions as a kind of intermediary
between external stimuli and different possible behavioral responses, an
intermediary that makes this variability of response possible. That plants lack such variability is thus a
reason to think they lack anything like such intermediary, conscious states.

A third
point -- one that combines specifically Aristotelian metaphysical considerations
with empirical considerations -- is that for the Aristotelian, sensation
naturally goes together with the other traditional characteristics of distinctively
animal life, namely appetite and locomotion.
The three features are not, in the Aristotelian view, merely accidentally
associated in animals, but form a kind of package. An animal is aware of various aspects of its
environment for the sake of the
motions toward or away from those aspects that that awareness makes possible,
and feels drawn toward or repelled by those aspects as a consequence. Thus the absence of locomotive and appetitive
powers in plants is evidence that awareness is absent as well, for awareness
would be pointless in that case. Indeed,
it might even be harmful. As Klubertanz
writes:

For example, grass lacks the organic
structure necessary for any form of sensation.
Moreover, it would be an evil for grass to have either sensation or
appetite. These activities would be
useless, for grass has no power of external action which could be modified
(controlled) by knowledge. The
activities would be directly an evil, for they would be a source of great
suffering without any compensating advantage.Nature is the source of operations for the
good of the being; a nature which by supposition would be the source of
operations for its own evil would be a contradiction. (p. 58)

Hence,
imagine that dry grass could feel the oppressive heat of the sun or experience
thirst and the craving for water. What
would be the point? It would not be able
to do anything about its circumstances and would thus, unlike an animal, suffer
without being able even in principle
to remedy the circumstances leading to that suffering. And this would violate the Aristotelian
principle that nature does nothing in vain. (But what about animals with disordered appetites
or wounded or deformed organs? Aren’t they
counterexamples to the claim that nature does nothing in vain? They are not, precisely because such animals are not in their natural state, precisely because they are in various ways deformed.)

Nor need one
accept the general Aristotelian philosophy of nature to see the force of this
consideration. For how could conscious
awareness evolve in a creature that was not capable of locomotion, given that the
way such awareness typically manifests itself is via behavior and given that it
is such behavior which would, presumably, be either adaptive or
maladaptive? Of course, the critic might
respond that awareness might have developed as a “spandrel” in the Gould/Lewontin
sense of being a non-adaptive byproduct of some other trait which was
adaptive. But there’s no point in
suggesting that some trait is a spandrel until we know it exists, and whether
awareness really exists in plants is precisely what is in question. Furthermore, it is hard to see what mechanism there could be for awareness
in plants even as a spandrel, given that they lack sense organs.

(Note also that
Michael Tye, arguing from a naturalistic rather than Aristotelian point of
view, has given similar reasons for denying that plants have qualia.)

Those who
claim that plants possess conscious awareness might at this point respond by
saying that the notion of a “zombie” (in the philosophical sense) shows
that conscious awareness has no adaptive value in any case, not just where plants are concerned but even where
animals and human beings are concerned.
But there are two problems with such a response. First, the Aristotelian will not agree that zombies
really are metaphysically possible; as I have argued in several places (e.g.
chapter 8 of Philosophy
of Mind and chapter 4 of Aquinas),
the notion of a zombie makes sense only against the background of a
post-Cartesian, mechanistic conception of matter and not on an Aristotelian
conception. Hence to appeal to zombies
would just be to beg the question against the Aristotelian.

Second, for
the defender of plant sentience to appeal to zombies would only undermine his
own case, for it would rob him even of the slender evidence on which that case
rests. For if there is no essential connection
between an animal’s locomotive behavior and conscious awareness, then there is
certainly no essential connection between the less dramatic, non-locomotive
responses of plants to their environments (growing toward the sunlight, etc.) and
conscious awareness.

So, there is
simply no good argument for awareness in plants. Those who claim otherwise are, I submit, not
thinking about the matter very carefully.
They ignore crucial differences between plants and animals while
magnifying superficial similarities. In
this respect their arguments are like those purporting to show that some apes
have linguistic abilities comparable to those of small children -- about which Noam Chomsky once aptly said:
“That's about like saying that Olympic high jumpers fly better than young birds
who've just come out of the egg -- or than most chickens. These are not serious comparisons.”

Bottom line:
If that weed seems to be “communicating,” that could just be ‘cause you’ve been smokin’ it…

42 comments:

But what if the entire world is pervaded by feeling intelligence? Or put in another way everything is in one way or another "packets" of quantum information.

This topic was covered by the very popular book in the 70's titled The Secret Life of Plants by Tompkins and Bird. It was of course dismissed as pseudo-science by the scientific establishment. I quite like the Amazon reviews. And even more so the book featured there titled The Secret Teaching of Plants by Stephen Buhner.

But here is a radical statement from another source: Among beings on Earth, human beings are unique - but only in the sense that they are as a species, significantly more advanced in the development of psycho-physical functions that are otherwise only latent or less developed in the case of the non-human world - of natural energies and elements, material shapes and cycles, simpler organisms, plants, trees, insects, fishes, birds, mammals, and the rest.

The non-human world is the immediate progenitor of the natural functions and the functional form of man. The world of non-human beings, of which the great trees are the epitome and the senior of all, is a great process, from which and relative to which and in which human beings are developed and developing , by virtue of a complex and ever-continuing event that functions at ALL levels, and not merely at the gross material level, of the psycho-physical cosmos.

Even if there was a general theory of consciousness as an epi-phenomenon of neural networks, plants wouldn't be conscious unless they exhibited nerve-like communication within themselves, or between themselves, as in Avatar. Consciousness as epi-phenomenon of neural network complexity has a number of other bizarre connotations, such as the possibility that nerve ganglia are actually conscious without any capacity to communicate with the outside world, or only a limited manner. It's possible (though far fetched) that gut ganglia, which are actually quite complex, our "second brains," might actually be conscious, with only the capacity to communicate by causing us gastrointestinal upset.

Koren: But if these facts can be explained equally well without awareness, as purely physical and mechanical responses to physical stimuli, this explanation has to be preferred, because it would be unreasonable to assume the working of a higher cause for effects which can be explained equally well by a lower cause.

Them's reductionist words! Of course, in general it is reasonable to stick with simpler causes when they suffice; that's basically Ockham's razor. But really one needs to look at the whole picture (by bringing in the subsequent points of how sensation is related to appetite and locomotion, etc.). Otherwise one can press the empirical evidence so far as to claim that everything about a plant is "just" mechanical responses. Not that Koren is a reductionist — I'm picking on a single sentence out of context — but the language struck me nonetheless.

"The vegetative powers of plants are shared by all organisms - nutrition, growth, and reproduction, along with all the adaptive powers that serve these basic functions or otherwise contribute to the proper functioning of the organism. Animals, however, belong to a higher grade of life, possessing specific animal powers - those of sentience, appetition, and locomotion.

Sentience at its most basic is the capacity and tendency for awareness of stimuli. Appetition is the capacity and tendency for seeking after and avoiding stimuli consequent upon awareness of them. Locomotion is the capacity and tendency for self-movement from place to place in fulfilment of appetition. Since sentience is the most basic property, we can define animals as sentient organisms."

Is Mesodinium chamaeleon an animal or a plant?

From the viewpoint of Aristotelian taxology, they are clearly animal. The confusion of modern science on this subject is the result of other, inferior forms of taxology that now hold prominence. Oderberg covers similar subjects in Real Essentialism.

Do all animals have conscious awareness?

Depends on the definition of "conscious". Sentience, again, may be described as "the capacity and tendency for awareness of stimuli." As Oderberg writes, "Because bacteria are unicellular, they have many different kinds of receptor to sense and interpret the diverse stimuli to which they are exposed. ... Why can't [plants] do what bacteria do, namely move in reponse to a massive array of stimuli of diverse kinds in unpredictable ways? They do not exhibit behavior that we could properly call flinching, or escaping, or avoiding stimuli - bacteria do all of these." Now, can bacteria be compared to cats and dogs in terms of "conscious awareness"? In some ways, yes; in others, probably not.

If "them's reductionist words", as has been noted (with proper qualification), perhaps it is possible to go in the other direction, by giving utterance to "subsuming words":

I once read a letter written by a young invalid, in which he told a friend that he had just found out he would not live for long, that even an operation would be of no help. He wrote further that he remembered a film he had seen in which a man was portrayed who waited for death in a courageous and dignified way. The boy had thought it a great accomplishment to meet death so well. Now - he wrote - fate was offering him a similar chance.

Those of us who saw the film called Resurrection - taken from a book by Tolstoy - years ago, may have had similar thoughts. Here were great destinies and great men. For us, at that time, there was no great fate; there was no chance to achieve such greatness. After the picture we went to the nearest cafe, and over a cup of coffee and a sandwich we forgot the strange metaphysical thoughts which for one moment had crossed our minds. But when we ourselves were confronted with a great destiny and faced with the decision of meeting it with equal spiritual greatness, by then we had forgotten our youthful resolutions of long ago, and we failed.

Perhaps there came a day for some of us when we saw the same film again, or a similar one. But by then other pictures may have simultaneously unrolled before one's inner eye; pictures of people who attained much more in their lives than a sentimental film could show. Some details of a particular man's inner greatness may have come to one's mind, like the story of the young woman whose death I witnessed in a concentration camp. It is a simple story. There is little to tell and it may sound as if I had invented it; but to me it seems like a poem.

This young woman knew that she would die in the next few days. But when I talked to her she was cheerful in spite of this knowledge. "I am grateful that fate has hit me so hard," she told me. "In my former life I was spoiled and did not take spiritual accomplishments seriously." Pointing through the window of the hut, she said, "This tree here is the only friend I have in my loneliness." Through that window she could see just one branch of a chestnut tree, and on the branch were two blossoms. "I often talk to this tree," she said to me. I was startled and didn't quite know how to take her words. Was she delirious? Did she have occasional hallucinations? Anxiously I asked her if the tree replied. "Yes." What did it say to her? She answered, "It said to me, 'I am here - I am here - I am life, eternal life.'"

By the way, I have some really neat Kirilian Polaroids my little brother took 30 years ago, if any Gaia worshipers or pantheists are interested.

I'll cut you a good price and throw in a cardboard altar [says Nike on the side] as part of the package. I found these holy images in a box in my parents basement, stored alongside some of his Estes rockets.

Gene Callahan: Daniel, dogmatically repeating the point under contention is always an unlikely way to resolve a dispute.

Since he was the first person to use the word "choice", he wasn't repeating anything. I think most people would take the claim that plants make conscious choices to be a further and more audacious claim than that they have experiences.

[Oderberg:] "They do not exhibit behavior that we could properly call flinching, or escaping, or avoiding stimuli..."They certainly do. They just do all of these things more slowly than do animals.

That's why he said, "properly". You could also call "losing a race" "winning… more slowly". But properly, it's still called losing.

Here's what Oderberg says: "My contention is that it is locomotion of the whole organism that gives evidence of sentience, not a mere reflex in one or other part of an organism that is otherwise rooted to the spot."

In addition, he explains the movements of plants like the Venus fly trap and the Mimosa pudica like so: "Nyctinastic movement (leaves folding and drooping at night) and seismonastic movement (folding and drooping due to warmth, contact, or agitation) are both explained in terms of a rapid decrease in the internal pressure of cells of the pulvinus (small swelling) at the base of the leaves of the Mimosa pudica, causing leaf drooping and contraction (Yamashiro et al. 2001). A similar mechanism underlies the behavior of Dionaea muscipula [Venus fly trap] (Hodick and Sievers 1989), with the flow of calcium ions crucial in both cases."

Can you point me to an exhaustive Aristotelian taxonomy?

I don't know of one off the top of my head, but Oderberg probably makes reference to one in Real Essentialism. I can't remember, though; and I'm not sure where that would be in the book.

The intelligent behavior of sentient rhododendrons having been brought recently to my attention, I, my sanity having been subsequently replivened, wish to offer some evidence in favor of the notion that my gums are sentient. (I hasten to point out to skeptics, scoffers and detractors alike that, however brittle the evidence may seem to be, it is evidence nonetheless.)

For example, a chip of a tooth once was left behind when the dentist extracted (most of) it. "By golly and by gum!", exclaimed the tissues. "This poor fellow has been orphaned! We know not whence its parent has gone, but if we allow the orphan to remain, the chances of a reunion will be nil. Come, let us swell so as to send the chip on its way. We shall, however, do it slowly over time. Yes. And this for two reasons: a) that the ride may be enjoyable; and, b) because an immediate expulsion following a sudden abandonment may constitute a one-two punch from which the chip may never recover. "

As may be seen, not only are my gums sentient, they are compassionate as well (which, alas, cannot necessarily be said of all sentient beings).

Oderberg: "Nyctinastic movement and seismonastic movement are both explained in terms of a rapid decrease in the internal pressure of cells of the pulvinus at the base of the leaves of the Mimosa pudica, causing leaf drooping and contraction."

Sure, everyone knows that, but so what? I hate to grumble about reductionist language again [disclaimer: that's a lie], but Oderberg could keep going with his "it's only calcium ions" explanations until he reduced the whole plant to an extra-complex complex of chemicals. It's not that what he says is wrong, it's that the way it's offered makes it sound as though that sort of reducing is acceptable to answer challenges against his theory, but not when materialists want to reduce everything to physics in support of their theory. If that were the right approach, then it would be correct to say, "Hey, plants are more complex than Aristotle thought, so let's call them animals instead!" But it's not, so it isn't. Does that mean there will be some things we can't figure out for sure, some grey areas, some fuzzy boundaries? Of course, just as there are in every area of life. The principles are clear, but that we can apply them only fallibly and approximately is common sense. It would in some ways almost be more helpful to say, "Of course a Venus fly-trap is a plant, what does it look like?!"

Oderberg despises reductionism, and he spends countless pages in that book tearing it down and defending holism. I don't think he was offering a reductionist account of the plants here; rather, he was just explaining how and why they move.

Glenn said, in response to some comment or other about plants not flinching: They certainly do. They just do all of these things more slowly than do animals.

Actually the second sentence is arguably not true, either; you're underselling your case on this point. Tropisms tend to be slow, because they deal with relatively reliable features of the environment or constant needs (light, water, soil, gravity). Some such reactions, like the closing of a Venus flytrap on its prey, are quite as swift a reaction as one would expect from animals with similar kinds of reaction. (There's a delay between the snap and the full close of a Venus flytrap, but there's good reason to think that this is a functional adaptation rather than mere slowness, and the actual snap is, of course, famously dramatic.) Such things are relatively rare, to be sure, but they do occur.

For my own part, I think a qualia-based distinction is a nonstarter, and response-based distinctions clearly can only be typological in character -- i.e., they identify something in the type 'plant', but (as with all typological classifications) kinds of plant may for various reasons diverge from type. But this is what one would expect: just as high-order estimative cognition has a wide range of similarities to low-order rational cognition, a sort of overlap, so high-order plant activity should have a wide range of similarities to, or even what could be seen as a sort of overlap with, low-order animal behavior. The idea that this would not be true seems to me to be Linnaean, not Aristotelian.

The specific issue of sensation, however, is not a matter of response but of what grade of abstraction the response requires (hence the emphasis on mechanism, flexibility and alternatives, and appetitive activity rather than response as such).

I'm confused about one thing in this post though, and that's the idea that animals experience qualia:

I've recently been looking at some of your old blog posts arguing for dualism. You have one post on qualia (http://edwardfeser.blogspot.com/2008/10/some-brief-arguments-for-dualism-part.html) where you argue that the human perception of qualia entails that the mind is immaterial. But if this is true, and animals also perceive qualia, then doesn't this entail that animals also have an immaterial mind? And if that's the case, wouldn't it then follow that animals also have an immortal soul?

1.Mr. Green, August 10, 2011 8:32 PM: "Dogs do have souls. It seems you're confusing everyday terminology with philosophical terminology, and even different philosophies. A good introduction to Aristotelianism (or Thomism) would lay out the groundwork for understanding what the point is here."

2.21st Century Scholastic, March 30, 2012 2:40 PM (notes have been added): "But a soul of a dog is immaterial too, yet it is not immortal. That's because its operations depend wholly on matter [(b)], while a human's intellectual activities do not [(a)].

Added notes:

(a) "We must conclude, therefore, that the human soul, which is called the intellect or the mind, is something incorporeal and subsistent." ST I, Q 75, A 2.

(b) "Wherefore we conclude that as the souls of brute animals have no "per se" operations they are not subsistent." ST I, Q 75 A 3.

3.Edward Feser, August 8, 2011 3:11 PM (same link as for 1. above): "...if it turned out that there are non-human animals which carry out intellectual activity -- apes, dolphins, whatever -- what would follow from that, on Aquinas's premises, is that they too have subsistent forms for souls."

(I do not mean to imply, via 1. above, that you, Ian, are "confusing everyday terminology with philosophical terminology"--quoting a 4-word sentence seemed a bit too anemic, so included some of what followed, that's all.)

What's your position on invertebrates (shrimp, insects, mollusks, etc)? They have a nervous system, and sense organs to drive it, but it is not centralized like that of humans and their biological relatives. That is to say, no brain, or at least a very radically decentralized one. It is harder to imagine what a self or soul is for such a creature, or what it is like to be one. Yet they perform a variety of cognitive feats including communication (among the social insects).

(props for quoting Chomsky btw, even though in this particular area he seems misguided to me)

What's your position on invertebrates (shrimp, insects, mollusks, etc)? They have a nervous system, and sense organs to drive it, but it is not centralized like that of humans and their biological relatives. That is to say, no brain, or at least a very radically decentralized one. It is harder to imagine what a self or soul is for such a creature, or what it is like to be one. Yet they perform a variety of cognitive feats including communication (among the social insects).

If bacteria are considered animals under A-T, then why would invertebrates be any different?

To build on Glenn's comments, in A-T phil. of nature animals and plants both have souls, which are just the forms of animate beings. Since form is the principle of act and matter the principle of potency in material beings, forms are by their nature immaterial. Animal souls, while themselves being immaterial, also carry on immaterial operations like sensation, which entails the intentional reception of form. I.e., a form exists immaterially in an animal's sense power(s) rather than physically. The same is the case for human beings, who also have the added powers of intellect and will. Unlike the internal and external senses, which are associated with and dependent upon physical organs (eyes, ears, brain, nervous system, etc.), these latter powers are not, and as a result, St. Thomas argues that the human soul is unique in being subsistent and able to survive the death of the body. This is not the case for plants and non-human animals since every operation carried on by their various souls is associated with matter in some way. Thus when these types of composite corrupt, their forms cease to exist as well. If you are interested in some of St. Thomas's argumentation in this regard, you can find his De Anima commentary and the Treatise on Man from the Summa Theologiae online.

@Brandon: "Such things are relatively rare, to be sure, but they do occur."

No, we have discovered they are not rare at all. They are rare *to our senses*. But plants behave in ways that can only be detected with specialized instruments. It is now well documented that many, many plants "fight off" insects attacks, for instance, certainly not a relatively constant feature of the environment. They just do it in a different way than animals do.

Gene, since I was pointing out that you were on this point not doing justice to the behavior of plants, by selling short their capacity for dramatic action -- yes, to our senses -- your argument is irrelevant and not to the point.

So, as I understand it now, animals do have immaterial souls, but the functions of these souls depend entirely on physical organs in a way that the human soul does not, so that when the animal dies, the soul dies with it.

If that's a correct understanding, does that mean that in Prof. Feser's argument re: dualism that I linked to, he is not proving that the human soul is immortal, but only that the modern theory of materialism cannot account for the immaterial aspects of the soul? (I recognize that there are other arguments that can be used to prove the immortality of the human soul, e.g. the argument from universals).

Glenn: If "them's reductionist words", as has been noted (with proper qualification), perhaps it is possible to go in the other direction, by giving utterance to "subsuming words"

Yes, I think that's a good point. Subsuming words are more readily interpreted poetically, I expect, whereas reductionist words are taken to be "more real" than the reality they describe. I don't think that was always the case, but of course past ages did not have all the details, or the successes, that we do, so there would have been less temptation. And certainly, the atomists we have had always with us….

To answer your questions, all forms whatever are immaterial. It's hard for moderns to think of matter and form in an Aristotelian way -- at least it was for me initially -- because it seems to me, people are more used to thinking or imagining matter along the lines of Descartes' res extensa, an extended thing. A thing for Aristotle would primarily be a substance, not a principle or cause of substance (i.e., a principle being that from which something flows and a cause being that upon which something depends for coming to be or existence; cf. V. Smith, A General Science of Nature, p. 7). Strictly speaking, principles and causes are not things in the sense of substance.

Thus in the A-T universe, all substances have an immaterial constituent, namely form. Some forms, like those of animals, carry on immaterial operations, like sensation, and are called "souls." Only one type of soul, namely the human soul, carries on operations not dependent on matter via a physical organ. (Though human souls do also carry on the operations of the sensitive powers associated with organs just like the lower animals do, the latter carrying on these operations to varying degrees according to their capacities and situation in the hierarchy of being.) This is why St. Thomas says the human substance can persist the corruption of the body, and not by virtue of it being immaterial. (Note: There is some dispute about this being the case in Aristotle because some commentators, unlike Sts. Thomas and Bonaventure, held for a separate Possible or Agent Intellects, which operate for all human souls (e.g., Ibn Sina). But that is kind of beside the point…)

The whole dualism/monism (e.g., materialism) dichotomy in modernity isn't at issue in A-T philosophy so much because there wasn't a need to explain the connection or interaction between two totally diverse substances (body and soul). There is only one substance, which has both immaterial and material principles. So I am my soul and body (composite), not just a body or a soul. There is more that could be said because separate forms or "Intelligences" (i.e., angels in Christian parlance) can exert their power in a place or over material being.

So, yes, I don't think Dr. Feser's point was to prove the immortality of the soul in that post so much as to argue that an account for "qualia" is problematic on both materialist and cartesian-dualist grounds.

My explanations may be a little confusing, however, because after reading that post I see that I have used terminology differently. When I say form is received immaterially or that the soul carries on immaterial operations, like sensation, I mean to say that the form sensed is received in an immaterial way vs. physically (e.g., seeing fire vs. being burned by fire). I think when Dr. Feser says that mechanism makes things like "qualia" "immaterial" (vs. material), he means it in the sense that it becomes completely spiritualized and has nothing to do with the body or connection with material reality. Of course, sensation as I have explained it is material in the sense that it happens in conjunction with physical organs. Similarly, we can speak of a form as a "material form" in the sense that certain forms are always or normally found with matter, unlike separated substances (Intelligences or God), which are not.

Rank Sophist: I don't think he was offering a reductionist account of the plants here; rather, he was just explaining how and why they move.

Certainly Oderberg isn't a reductionist, and that's only a partial explanation; but if the flow of calcium ions, etc. does not prove that the Venus fly trap is not a plant, how can it prove that it is not an animal? It would make sense to say, "Such-and-such is not an animal because it can be reduced to physics, and is therefore just a mechanism", but if the reduction can apply to that particular facet of something that is a plant, then the same reduction could apply to something that is an animal. Unless he wants to claim that the seeming animalistic properties can be reduced (and thus explained away), but there are vegetable properties that cannot, so the thing must be a vegetable.

However, as I far as I recall, Oderberg doesn't come out and say, "Even after physics and chemistry are closed books, when we know everything about them, there will still be something about plants that they cannot explain." Aristotelians in general don't, because it's not necessarily true. (Otherwise, all it would take is some scientist to come up with a complete explanation for a plant in terms of chemistry and physics, and Aristotelian metaphysics would be refuted, oops.) Something might be reducible to physics because it's just a mechanism, or might look like it does because it's a organism that virtually "reduces" to its parts. Appearances can be deceiving.

Of course, common sense tells us that overall, appearances aren't all that deceiving. God could have created a fun-house universe in which nothing is as it seems, but He didn't. Prof. Feser has written on common sense before: we should reject it when it doesn't make sense — but we shouldn't when it does make sense. I can't give you an algorithm for proving whether someone is a real human being or a technologically advanced robot or a projection of my solipsistic mind — but common sense tells me that other people are other people, and my philosophy has a perfectly good explanation of how that can be, so the rational conclusion is that the people I see all around me are indeed real human beings. Investigating their DNA would be a perfectly good answer, but to a different question.

Well, first you complain that Daniel is being too loose in his definitions, and now that I'm not being loose enough!

Winning a race is about speed, but "flinching" is about "moving away from bad conditions." Plants do that.

There are robots that can flinch when you poke them with a dental drill (they're used for training dentists), but that doesn't make them animals. Even if plants qualify as unequivocal flinchers, it doesn't immediately follow that they are animals either. In the response you posted, you say that you understand the Aristotelian position, and seem to suggest that if only Aristotle had known how complex plants were, he would have called them animals instead. But I think that is to get the whole approach to Aristotelianism backwards.

The reductionist has a checklist of attributes — meet those properties and you've got a vegetable (or animal, or mineral). There is nothing more to being that kind of substance than meeting the checklist. Under A-T, what makes something the kind of substance it is is having the right substantial form. The substance may or may not satisfy any checklist. (Even properties or behaviours natural to that substance might be missing if the substance in question is defective — but a deformed animal is still an animal and not a plant, and so on.)

And that's why fungi are adequately classified as "vegetable substances" in the Aristotelian scheme, as already indicated. (It doesn't matter what biologists call it; they are not investigating substantial forms, and so have different things to check off on their list. My dinner menu has yet different goals, so it's fine for me to call a tomato a vegetable instead of a fruit.) Aristotle knew full well that there are different categories of "plant substances". Common sense tells us that mushrooms and Venus fly-traps are neither mineral nor animal, and the intricate behaviour of plants does not require us to forsake that obvious conclusion.

(Hence Oderberg's explanation of how certain mechanisms work in plants, showing they do not require an animal soul. Presumably he should be read as saying, "Given that a Venus fly-trap is a plant, here's how we can analyse its movement…" And being a diehard Aristotelian-type himself, no doubt that's how he's thinking of it. It's not his fault if the modern anti-aristotelian atmosphere can confuse me sometimes — but if I have trouble following, many others will also. So I guess this can be taken as a plea for A-T writers to belabour the (to-them!) obvious, if only as a practical matter.)

"(It doesn't matter what biologists call it; they are not investigating substantial forms, and so have different things to check off on their list. My dinner menu has yet different goals, so it's fine for me to call a tomato a vegetable instead of a fruit.)"

I think this is an important point, and I remember Oderberg stressing this at some point in "Real Essentialism". Because the Aristotelian classificatory scheme (the Porphyrian tree) concerns the essence of a thing it will naturally be different than the tree seen in modern biology adapted and handed down by Linnaeus. The former is clearly intended as a metaphysical classificatory scheme, and furthermore, is not concerned temporally with what a thing once was (for example, ape-to-man evolution, provided its validity).

Gene Callahan: Daniel, there is no such thing as "two identical plants," so the "evidence" is nonsense.

I'm starting to think that you only read a post until you find something to object to. This is the second time now that you've objected to something I've said when the answer to your objection is contained in the very next sentence!

This time you objected to my speaking of "two identical plants" but I also gave the example of "the same plant, under identical conditions, subjected to the same stimulus".

Of course you'd have had to read one sentence further into my post to see that!

About Me

I am a writer and philosopher living in Los Angeles. I teach philosophy at Pasadena City College. My primary academic research interests are in the philosophy of mind, moral and political philosophy, and philosophy of religion. I also write on politics, from a conservative point of view; and on religion, from a traditional Roman Catholic perspective.